Digital electric power can be characterized as any power format where electrical power is distributed in discrete, controllable units of energy. Packet Energy Transfer (PET) is a new digital electric power protocol that has been disclosed by inventor Stephen S. Eaves in U.S. Pat. No. 8,068,937, “Power Distribution System with Fault Protection Using Energy Packet Confirmation”. A representative digital electric power distribution system using PET protocol is described in Eaves' U.S. Pat. No. 8,781,637 B2 (Eaves 2012).
The primary discerning factor in a digital power transmission system compared to traditional, analog power systems is that the electrical energy is separated into discrete units, and the individual units of energy can be associated with analog and/or digital information that can be used for the purposes of optimizing safety, efficiency, resiliency, control or routing.
As described by Eaves 2012, a source controller and a load controller are connected by power transmission lines. The source controller of Eaves 2012 periodically isolates (disconnects) the power transmission lines from the power source and analyzes, at a minimum, the voltage characteristics present at the source controller terminals directly before and after the lines are isolated. The time period when the power lines are isolated was referred to by Eaves 2012 as the “sample period” and the time period when the source is connected is referred to as the “transfer period”. The rate of rise and decay of the voltage on the lines before, during and after the sample period reveal if a fault condition is present on the power transmission lines. Measurable faults include, but are not limited to, short circuit, high line resistance or the presence of an individual who has improperly come in contact with the lines. Since the energy in a PET system is transferred as discrete quantities, or quanta, it can be referred to as “digital power”.
A representative digital power system as originally described in Eaves 2012 is shown in FIG. 1. The system is comprised of a source 1 and at least one load 2. The PET protocol is initiated by operating switching means 3 to periodically disconnect the source from the power transmission lines. When the switch is in an open (non-conducting) state the lines are also isolated from any stored energy that may reside at the load by isolation diode (D1) 4. Capacitor (C3) 5 is representative of an energy storage element on the load side of the circuit.
The transmission lines have inherent line-to-line resistance (R4), 6 and capacitance (C1) 7. The PET system architecture, as described by Eaves 2012, adds additional line to line resistance (R3) 8 and capacitance (C2) 9. At the instant switch 3 is opened, C1 and C2 have stored charge that decays at a rate that is inversely proportional to the additive values of R4 and R3. Capacitor (C3) 5 does not discharge through R3 and R4 due to the reverse blocking action of the isolating diode (D1) 4. The amount of charge contained in C1 and C2 is proportional to the voltage across them, and can be measured at points 10 by a source controller 11.
As described in Eaves 2012, a change in the rate of decay of the energy stored in C1 and C2 can indicate that there is a cross-line fault on the transmission lines. The difference between normal operation and a fault, as presented by Eaves 2012 is illustrated in FIG. 2.
US Patent App. Pub. No. 2015/0207318 A1, “Digital Power Network Method and Apparatus”, hereafter referred to as “Lowe 2014”, introduced the concept of multiple sources of power and multiple loads connected together safely in a digital power network using Packet Energy Transfer. The concept of a power control element (PCE) was introduced in Lowe 2014 as a primary component in a digital power network. An illustration of a power control element 12 is depicted in FIG. 3.
Power control elements perform one or more of the following functions:                perform safe transfer of energy under Packet Energy Transfer (PET) protocol,        convert from analog power to digital power under PET protocol, or vice versa,        convert and/or control voltage and/or current, and/or        switch power from one PET channel to another PET channel within the network.        
A PCE can be employed to manage the charge and discharge of an energy storage device, such as a battery. PCEs can manage the extraction of energy from a power source, such as a solar panel; alternatively, PCEs provide power to a load, such as a light emitting diode (LED) light.